PACKAGES would grow, substantially, but wouldn't be harder to
maintain; in fact PACKAGES could be just a naive concatenation of
everyone's DESCRIPTION files.

For that matter, if you would be willing to add the extra data to
PACKAGES, the current implementation would work, and I could just run
my hacked version and get at what I wanted. But I know of at least
one other package-heirarchy maintainer who might like this, and
subsuming it in the base function would be nice.